Michael Reilly

Okay, so it's not G889 that humans colonized in the TV series, but it's the closest astronomers have found yet. Weighing in at around 5 Earth masses and 1.5 times Earthly diameter, GJ 436c (which orbits the star GJ 436) is the smallest rocky exoplanet ever discovered. It still has many of the wonky traits of other exos like a 3-week long day and a 5.2 day-long year, but preliminary calculations suggest the toasty planet could be nice and balmy at the poles — perfect for an extended beach vacation in the Leo constellation.

Most of the 280 or so exoplanets discovered so far have been searing gas giants that orbit their stars closer than Mercury is to the Sun. But GJ 436c is the latest in a growing class of rocky exoplanets called 'super-Earths' that are getting smaller by the day, thanks to a new method planet-hunting astronomers are using to measure stars' gravitational wobble:

Ignasi Ribas, lead author of the study from the Spanish Research Council (CSIC), says: "After final confirmation, the new exoplanet will be the smallest found to date. It is the first one to be identified from the perturbations exerted on another planet of the system. Because of this, the study opens a new path that should lead to the discovery of even smaller planets in the near future, with the goal of eventually finding worlds more and more similar to the Earth."